docs: log_line_prefix session id fix

Restore 4-byte designation for docs.  Fix 9.3 doc query to properly pad
to four digits.

Backpatch to all active branches

Per suggestions from Ian Lawrence Barwick

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d95b8a1b339cd0b821d92888e69bebfc6c8587d6..ab40ea76122545673c1b34f7be9e9478fef348c2 100644 (file)
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -3568,7 +3568,7 @@ local0.*    /var/log/postgresql
          </informaltable>
 
          The <literal>%c</> escape prints a quasi-unique session identifier,
-         consisting of two hexadecimal numbers (without leading zeros)
+         consisting of two 4-byte hexadecimal numbers (without leading zeros)
          separated by a dot.  The numbers are the process start time and the
          process ID, so <literal>%c</> can also be used as a space saving way
          of printing those items.  For example, to generate the session